Inlet manifold and methods for increasing gas dissociation and for PECVD of dielectric films

Abstract

An inlet gas manifold (11) for a vacuum deposition chamber (10) incorporates inlet apertures (31) which increase in diameter or cross-section transverse to the direction of gas flow (22). The aperture configuration increases the dissociation gases such as nitrogen and, thus increases the rate of silicon nitride deposition provided by nitrogen gas chemistry, without requiring the use of reactants such as ammonia. While one could use ammonia in the deposition gas chemistry if desired, the process provides the option of completely eliminating ammonia The inlet manifold (11) containing the increasing-diameter gas inlet holes (31) provides enhanced control of the process and the deposited film, and is also useful for forming other dielectrics such as silicon oxide and silicon oxynitride. In particular, silicon oxynitride films are characterized by low hydrogen content and by compositional uniformity.

What is claimed is: 
     
       1. In an RF vacuum deposition chamber system, a gas inlet manifold which is an RF electrode and includes at least a plurality of gas inlet holes therein, each hole comprising an outlet at the processing side of the gas inlet manifold and an inlet spaced from the processing side, said outlet being larger than said inlet, for increasing the dissociation by RF energy applied to the gas inlet manifold of gas passing through the holes. 
     
     
       2. The RF vacuum chamber of claim 1, wherein lines connecting the opposite sides of the inlet to the corresponding sides of the outlet subtend an angle of about 15°-60° . 
     
     
       3. The RF vacuum changer of claim 2, wherein the hole cross-section is conical. 
     
     
       4. The RF vacuum chamber of claim 3, wherein the sides of the conical hole subtend an angle of about 30° . 
     
     
       5. The RF vacuum chamber of claim 2, wherein the hole cross-section is concave. 
     
     
       6. The RF vacuum chamber of claim 1, wherein the hole cross-section is conical. 
     
     
       7. The RF vacuum chamber of claim 6, wherein the sides of the conical hole subtend an angle of about 30°. 
     
     
       8. The RF vacuum chamber of claim 1, wherein the hole cross-section is concave. 
     
     
       9. The RF vacuum chamber of claim 1, wherein the hole cross-section is selected from parabolic and hyperbolic. 
     
     
       10. The RF vacuum chamber as in any of claims 1, 2, 6, 7, 8, 9 or 3-5, wherein the holes are formed in a pattern of interlocking face-centered hexagons in a face plate of the manifold in which the individual holes define an edge of one associated hexagon and are at the center of a second associated hexagon. 
     
     
       11. The RF vacuum chamber of claim 10, wherein the gas is nitrogen.